Nicki Lynn Aycox (born on May 26, 1975 in Hennessey, Oklahoma) is an American actress best known for her role as Syl on the series Dark Angel and Stella Vessey on the dramedy Ed. She also had a stint as the unreliable sister of Detective Rush on the series Cold Case and as Pvt. Brenda "Mrs B" Mitchell in the FX series Over There. She is also the first actress to appear on "CSI:Crime Scene Investigation" as Captain Jim Brass' daughter, Ellie . She currently has a recurring role on Supernatural.